In recent times there has been an increase in the use of portable two way radios, commonly referred to as walkie-talkies, in a variety of settings. Walkie-talkies have been long used in work-related activities, for example to let employees remain in contact with one another and with a central office. Typical uses include warehouse and retail settings, where workers are requested to move goods, and where specific employees can be summoned. Portable transreceivers are routinely used as an alternative to telephone communications in any setting where the communicating users are relatively close to one another. The security and public safety fields have been early users of walkie-talkies and related two way radio equipment, to help agents stay in contact and receive instructions.
More recently, as two way radio devices have become less expensive, recreational and family uses have become increasingly common for these devices. Family members use simple walkie-talkies to stay in touch and find each other, for example when hiking, skiing etc. Two way radios of various levels of sophistication have found a place in all types of sport and recreational events, to enhance safety and to increase the information level of the participants. Walkie-talkies have become almost a fashion accessory in certain cases, and have become available in various shapes and colors, ranging from inexpensive low power units to sophisticated units capable of encrypting their transmissions.
Typical walkie-talkies and other types of two way radios, however, suffer from various drawbacks that limit their usefulness in many situations. Perhaps the most serious limitation is the range of these devices, which often is very limited. Since the voice transmissions are carried from one station to another by radio waves, any physical obstacles to the propagation of those waves affects the range and quality of the received transmission. Most publicly available non-licensed 2 way radios are limited to a small power output (5 watts or less), which further limits their range. Interference from other radios or various sources of electromagnetic noise also affects reception quality. In addition, there is no mechanism in conventional radios to prevent two transmissions on the same frequency (or channel) from interfering with each other, without the source or the recipient of either transmission being aware of the interference. In many cases users have to carry various electronic tools such as portable computers or scanners, and having to carry an additional transreceiver device can be very cumbersome.